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I thought INTENSE recommended the idle LTFTs be tuned to 0 not +16. In another thread where I asked this question, everyone told me Zoom was the only vendor that recommended a +16 tune at idle.

I have mine tuned to 0, should I change it to +16?
 

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So which is it +16 or 0? This + 16 is something that seems to have come up within the last 2-3 mos. Or at least thats when I started to hear about it. I looked at the tunning thread that Chris from intense wrote and he clearly states LTFT should be 0. It would bw nice if someone could clear this up.
 

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LTFT should be at 0 for stock, most modded cars. IIRC its cars with major work (ie. cams, heads and such) might need different values if the PCM isn't specifically coded for the mods...
 

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Hey John,
I'm from Riverview. I swear I have seen your car on Sibley road on more than one occasion. There aren't many modded orange GP's around. Sharp car.
 

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Yep that was probably me...I drive on Sibley Rd all the time. I see a few Orange GPs around here, but none are modded (at least from what I can see..)...there's a couple of GP'ers downriver...we should all get together when its warmer out....you are member of a local club? MIGPC? MCCGPC? I am a member of MIGPC...
 

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Sounds great. The Downriver cruise would be a great place for us to all meet up and show off our cars. But, we don't have to wait for that. I'd love to get togeather with some other GPers in the downriver area. Dude, I love the way your car looks. I admired it the first time I saw it. I drive a heavily modded black 98' sedan. I have 17" enkei rims and power slot rotors all the way around. Gives the car a distinctive look. Maybe you've seen me cruising in it.
 

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Ok quick question. Assuming youre not getting any knock retard, around where should your Ign timing be at during WOT? I did a log of my car the other night and got roughly 1.5-3 points of KR, but I was also only seeing 8-11* of advance, telling me that if I didnt have any knock I would be seeing roughly 12* of advance. Shouldnt it be higher than that? My IAT's were also around 32*(its cold here brrrrrr) so its not like it was breathing the air from hell. Although my o2's were around .910 so I was running a little lean.
But back to my original question. How much advance does the average GTP run at WOT assuming no knock??
 

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NY GTP said:
Ok quick question. Assuming youre not getting any knock retard, around where should your Ign timing be at during WOT? I did a log of my car the other night and got roughly 1.5-3 points of KR, but I was also only seeing 8-11* of advance, telling me that if I didnt have any knock I would be seeing roughly 12* of advance. Shouldnt it be higher than that? My IAT's were also around 32*(its cold here brrrrrr) so its not like it was breathing the air from hell. Although my o2's were around .910 so I was running a little lean.
But back to my original question. How much advance does the average GTP run at WOT assuming no knock??

There are high octane and low octane tables, plus many adder/subtracter tables that will add/remove timing based on engine load, coolant temp, IAT , etc... It also depends how much load the motor is seeing

Looking at some stock GTP .bins , looks like under heavy load it doesn't run much timing at all... Looks like 11* at higher RPMs and heavy load isn't uncommon at all... at 32* there's no IAT Spark correction and ECT of 158* - 212* don't pull or add any timing ...

The PCM learns based on how much knock it sees, it will start closer to the low octane tables and work its way up to the high octane, however if it's continously seeing knock it'll spend more time closer to the low octane tables
 

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Excellent! I agree, the best "layman's" terms of sensor functions I have ever heard! Even those of us that did know these, this should make it easier to explain to others "such as the wife when you are asking for a few hundred bucks for parts!". Patiently waiting to hear the "simple talk" you have for us next!
 

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just started to knock

Just installed the 3.4 pulley and I hear knocking on mild accelerations (sounds like low octane gas but i use 94). Is this due the the stock pcm? I have an intense pcm and a hp tuner vcm suite being delivered this week. mods are intense 3.4 pulley, intense fenderwell intake, 104 autolites, and 180 stat.

please advise
thanks steve
 

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If the idle was at +16.4 wouldn't that make it harder to tune the LTFT's for cruising and WOT? Isn't that why you are supposed to tune for idle then cruise, then WOT in that order? I'm just trying to figure out if I need to be at +16.4 or not.
 

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KR Issue

Guys I read Chris greens/the whole thing on KR/Knock Retard Well writen I am having a KR issue My 00 GS Mods are 3.4 mod pulley Vs Cam.factory gutted bx. TR6s [email protected] 180 thermo, 3 inch Dn. pipe but the factory Flex was used,2 1/2 exhaust no uben no res. Factory muffler used, I am seeing 5-6 points kr 26 degrees out also 40 degrees out The PCM is factory tuned. Timming was retarded to 8-9 degrees WOT Any suggestions Thanks Randy
 

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hello everyone.
im new to this entire 3800 situation. i bought a 98 gtp last night. it has a 3.4" pulley, Stegemeier rebuilt supercharger, transmission cooler, MSD wires and some other slight mods (i dont believe there are any other engine mods but i will check). anyways...i was told today by a friend who has an amazing gtp that i need to get my exhaust done asap. he said i need to get a new down pipe and different set up... i am planning on getting a different set up anyways but i just want to know about the down pipe. im not motor illiterate im just new to a supercharged 3800... anyone who has advice for me please let me know. i appreciate anything anyone anyone can tell me.. thanks in advance
 

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A more basic "101"

The following are exerpts taken from private mails I've been sending to another forum member in regard to tuning 101. This info is very basic for those who feel overwhelmed!

Basically it goes somewhat like this(simplified version, more to come later): The PCM controls the air fuel mixture. It also controls other things but let's just focus on AFR for now. It has 2 main operating modes, "open loop" and "closed loop". In closed loop operation the "closed loop" term means that the PCM sends it's AFR signals and the Oxygen sensor reports back to the PCM how well of a job it's doing at keeping the AFR at 14.7 to 1 (this is the normal AFR for a stock car) Open loop is when the PCM doesn't read the O2 sensor. This only occurs when there is a problem in the O2 sensor circuit or the engine has just been cold started and the O2 has to warm up before it works. That's why later model cars have an O2 sensor with a heater built into it to enable closed loop at an earlier engine temperature. The PCM also uses other sensors to calculate AFR. The MAP and MAF sensors tell the PCM how much air is going into the engine. The PCM has to know this to determine how much fuel is needed to maintain that 14.7 to 1 ratio. It also reads the coolant sensor, though this sensor is used for many other things it also is used to measure how much air is coming into the engine because the colder the air the more dense the air hence more fuel is needed to maintain 14.7-1. As the engine warms, the coolant temp sensor signals the PCM to cut back on fuel and the O2 sensor confirms when it does. Got it ? I'll stop here for now. Let me know if I'm being too elementary or moving too fast though the explanations. It's a bit overwhelming at first but if you enjoy learning like I do you'll find all this stuff fascinating and you'll pick it up quickly. Take care man, good hearing from you again, Billy
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OK, so here we go with the Engine Coolant Temperature Sensor, aka ECT or CTS. This sensor is a "negative coefficient thermistor" meaning it is a resistor inside a housing that increases it's resistance in ohms as temperature decreases (some cars use positive coefficient therm's that increase resistance as temp. increases). The Intake Air Temperature Sensor, aka IAT works the same way as the CTS, more on that one later. The PCM uses the CTS reading to determine engine temperature for many reasons. A colder engine needs more fuel to keep it running so when the PCM "sees"
-15*F from the CTS it increases the width of the injector pulse or in other words keeps the injectors open for a longer period of time to add more fuel. During this stage of operation the AFR (air fuel ratio) isn't kept at 14.7 to 1 as we discussed before. It is more like 11-1. ie richer because the ratio is 11 parts air to 1 part of fuel instead of 14.7 parts air to 1 part fuel. The lower the AFR's left number the richer it is. Consequently a hot engine needs less fuel or it will flood, stall, run poorly and use too much fuel. This "AFR vs. CTS " program in the PCM can be directly rewritten by the HPT, it has a scale beginning at -40*F and goes to something ridiculous like 284*F (like you'd ever run an engine that hot!). We'll discuss optimum AFR's later. The CTS signal is also used by the PCM to determine ignition timing. Due to the richness of a cold engine it needs a lot of timing advance to keep it running. We'll deal with timing later. The PCM also uses the CTS signal to determine when to apply the TCC (torque converter clutch). If the clutch is applied before the engine reaches operating temperature the car will buck and surge due to the heavy load on the cold engine. It would probably cause the plugs to foul also. Now-a-days the CTS signal is also used for the temp gauge in the dash, cooling fans and a few other things like disabling the A/C comressor in the event of overheating. I'll stop here for now, I know this can be too much at once. Food for thought... What if the CTS failed and it's resistance was infinite or wide open? It would start up thinking the engine temperature was -40*F. If it started at all, it would idle really fast - because the CTS signal is also used by the PCM to control fast idle. And it would be running so rich it could foul the plugs and blow black smoke.
What if you were driving and you noticed your cooling fans weren't coming on and your temp gauge was not reading any temp at all? That's right, an open coolant sensor making the PCM think it was -40*

The PCM has "failsafe" software to avoid problems due to failures like this from affecting the engine. For example: if this senario occurred where you know the CTS just bit the dust you wouldn't feel the engine run any different. Why? Because the PCM "knows" that the engine temp can't radically change in an instant. It's smarter than that. If you had the car running and unplugged the CTS you wouldn't notice any difference in the way the engine ran. You would however turn on the check engine light and set a fault code. The HPT can rewrite all these tables that use info from the CTS. It can rewrite cooling fan on and off temps, TCC engagement temp, fast idle speeds at differing temps, AFR at different engine temps, A/C compressor disablement, etc.(too many to list here) Suffice it to say it can correct just about any problem that occurs as a result of the modifications we do.

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OK, I guess the next thing to cover is MAF and MAP sensors. You may have researched this already so please bear with me if I'm repeating what you know. This is one area you'll need a very thorough understanding of, but you'll see and hear so much about it you'll eventually 'get it'.

MAF and MAP, 'Mass Air Flow' and 'Manifold Absolute Pressure' sensors basically tell the PCM how much air the engine is taking in at any particular moment. This info helps the PCM determine how much fuel to feed the engine. As we discussed before, it does this by varying the injector pulse width (aka injector 'on' time). The difference between the two are, MAF weighs the air coming into the engine and outputs a frequency signal to the PCM. The PCM then translates this frequency into grams of air per second.
MAP uses engine vacuum or boost inside the intake manifold. MAP outputs a voltage from 0 to 5 volts and is calculated by the PCM into either inches of mercury or kilopascals of pressure. When you hear of 'speed density' tuning, this refers to an engine that is only using MAP to help the PCM calculate the fuel ratio. MAP is more sensitive to minute changes in airflow where MAF is better at reading large amounts of air flow accurately. You'll be hearing a lot about MAF vs MAP and all the confusion surrounding the two. I've posted may times on the subject. You really don't need both of them to operate your engine. They're only both used now-a-days because emission standards have become so tight the PCM needs both of them to be dead on accurate. MAF is good at reading constant airflow or gradually changes in airflow but not small, minute changes. There are many different types of MAF sensors, 6 or 7 that I can think of right away. Ours is the frequency output type. As I stated earlier, it sends a variable frequency signal (0 to 11,500 Hz) to the PCM which the PCM translates into grams per second. Most tuning on our cars involves MAF in one way or another and most of the tuning tables in the HPT programs involve MAF output vs. XXX.

ie. MAF Frequency vs. Airflow - This table in HPT allows you to rewrite the PCM's base program that converts the MAF's output signal into grams per second. This allows you to change what the PCM 'thinks' a signal of 5000Hz of MAF output is in grams of air per second. If the car runs too rich at 5K Hz then the PCM is thinking there is more air coming into the engine than there really is. You would then rewrite a smaller amount of airflow at that specific frequency. Yes this is quite complicated but like I said you'll see so much of this it will become second nature. The MAP tables in the PCM can be rewritten the same way. I'm going to stop here for now. There is much more to be said about this subject but as the old saying goes 'Rome wasn't built in a day'.

Till next time, Bill
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This is as far as I've gotten there is still much to cover... Later Dude!:)
 
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